This invention relates to a kick starting apparatus for a motorcycle for driving a crank shaft in response to the rotation of a kick shaft driven by a kick operation.
A motorcycle includes a power transmission system generally comprising a crank shaft, a primary drive gear operatively connected to the crank shaft, a primary driven gear engaged with the primary drive gear, a clutch, a counter shaft operatively connected to the clutch, a transmission drive gear train, a drive shaft engaged with the transmission drive gear train, a drive sprocket gear mounted to the drive shaft, and a chain connected to the drive sprocket gear.
A kick starting system is arranged in connection with the power transmission system of the structure described above. The kick starting system comprises a kick shaft rotated by a kick lever, and a kick drive gear is mounted on the kick shaft to be rotatable. The kick drive gear is always engaged with a kick idle gear which is mounted at one end thereof on the drive shaft of the power transmission system to be rotatable.
A dog piece is mounted on the kick shaft by way of a helical spline and a dog is mounted on the side surface of the dog piece. This dog is positioned at a portion corresponding to the location of another dog mounted on the side surface of the kick drive gear. The rotation of the kick shaft causes the helical spline to displace on the kick shaft and engage the dogs with each other. In the engaged state, the kick shaft is rotated together with the dog piece and the kick drive gear.
In response to the rotation of the kick drive gear, the crank shaft is driven through the engagement of the kick idle gear, the kick driven gear engaged with the primary driven gear, the primary drive gear, and, hence, the crank shaft.
After the driving of the crank shaft, the rotation of the crank shaft is transmitted to the kick drive gear, which is then overrun, and the dog piece is thereby returned to separate the dogs from each other, whereby the kick shaft is released and returns.
Around the kick shaft is mounted a kick shaft return spring in the form of a coil spring. The inner free end of the return spring is engaged with the kick shaft and the outer stationary end thereof is engaged with a stopper bolt screwed with a threaded hole of the crank case.
With the kick starting system of the motorcycle of the construction described above, the stationary end of the kick shaft return spring is secured to the crank case through the stopper bolt which is screwed with the threaded hole of the crank case. The usage of such a stopper bolt requires a space for location and involves manufacturing cost thereof as well as the increasing numbers of the members to be assembled.